Manufacture of starch



July 26, 193s. A, H, KELUNG 2,124,779

MANUFACTURE oF sTARcH v Original Filed June 5. 1933 2 Sheets-Sheet 1 /ff@al 0' "l mez F52/ 190@ Jl; 22; y

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@Alfred/922,12; f? M+ gg: A Orf/@S July 26, 1938. A, H. KELLlNGMANUFACTURE OF STARCH 2 Sheets-Sheet 2 Original Filed June 5, 1935 QS whPatented July 26, 1938 UNITED STATES PATENT OFFICE MANUFACTURE or sTARcHOriginal application Juned, 1933, Serial No. 674,365. Divided and thisapplication June 4,

1936, Serial No. 83,540

15 Claims. y (Cl. 127-68) This invention relates to the manufacture ofstarch from corn by the wet method; and in particular to a process inwhich all, or substantially all, of the process waters (except the steepWater and the water absorbed in the discharged solids) are used back inthe process for the purpose of saving substances, soluble and insoluble,contained therein and preventing the pollution of streams which resultsif these process waters are discharged from the factory. v i' In themanufacture of starch from corn by the wet method it has been customaryto steep the corn, comminute it, and subject it to separating operationsin water for removing the germs, bran and liber. These separatingoperations yield streams of mill starch, so called, consisting of thinmixtures of starch, gluten and water; and it has been the usual practiceto cause the mill starch to be passed over starch tables on which thestarch is deposited and from the ends of which the gluten and majorportion' of the Water tail off. The starch is then removed from thetables, usually by flushing, and is dewatered and washed With freshWater in washing lters. 'Ihe water containing the gluten is allowed tostand in gluten settlers for the recovery of the gluten. The processwaters from the starch washing operation and from the gluten settlersare returned to the system for re-use in the operations upon the cornmaterial subsequently treated therein.

The water used for steeping the corn is withdrawn to evaporators inorder to recover the soluble substances therein which have value as aconstituent of cattle food and for other purposes.

In copending application of Alfred H. Kelling, Serial No. 675,412, fliedJune 12, 1933, and in application Serial No. 674,365, led June 5, 1933,of which the present case is a division, methods are disclosed for usingin a particularly advantageous manner, centrifugal machines foreffecting the separation between the starch and gluten that hasheretofore been accomplished by the tabling operation. According tothese inventions the centrifugal machines and the otherinstrumentalities for carrying out the process, are arranged so that, inthe rst place, all process Waters may be re-used in the process, (exceptfor the steep water and the water absorbed in the discharged solids);and,in the second place, the process water which is most highly infectedwith micro-organisms and which contains the largest amount of solublesubstances, and other impurities, specifically the water from the glutensettlers, may be used exclusively in the steeping operation, that is inthe stage of the process from which solubles are withdrawn for recovery;while the other process waters, which have less opportunity to stand anddevelop micro-organic activity than the gluten water and which containsmaller quantities of soluble substances and other impurities, arere-used in the later stages of the process, to wit, in the germ andcoarse and ne slop separating operations. Furthermore, the centrifugingof the mill starch is carried out in such a manner that solublesubstances are elimivwhiter starch is obtained since the impuritieswhich are concentrated in the process water that is used exclusively forsteeping include the substances which tend to give corn starch ayellowish tinge. No inconvenience is experienced in returning to thesteeps a water more or less highly infected with micro-organisms andcontaining relatively large quantities of solubles. The steepingoperation is performed on the corn material in the form of unbrokengrain not particularly susceptible to organic activity or to thepresence of soluble impurities in the steep water. The steeping iscarried on at relatively high temperatures and in the presence ofconsiderable quan'- tities of sulphur dioxide and these factors inhibitmicro-organic activity. The separating operation-the germ, coarse slopand fine slop separations-are, on the contrary, carried on at relativelylow temperatures and with relatively small sulphur dioxide concentrationand moreover the material is in a finely divided state peculiarlysusceptible to micro-organic activity and to contamination by solubleimpurities. The quality of the starch is therefore much improved bykeeping the operations subsequent to steeping as free as possible frommicro-organisms, products ci micro-organic activity and soluble andcolloidal impurities.

In application 674,365, of which the present application is a division,the light starch and gluten liquor from the fine slop wash (.ne slopmill starch) is used as a washing or counter-current liquid in the firstcentrifugal; the centrifuging 0p eration being preferably a multiplestage operation with the centrlfugals arranged on the counter-currentprinciple. Fresh water is used as a wash liquid in the later stages ofthe centrifuging operation, the overilow from the i'irst centriiugalgoing to the steeping system, through the settler, in part at least;while the overflow from the second centrifugal is returned to the fineslop wash to be used as a wash water. By this arrangement the water usedin the rst centrifugal for displacing the water in the mill starch,which latter contains a large quantity of soluble substances, is a waterhaving a low solubles content, due to the fact that the fine slop iswashed with water from the later centrifugal operations which use freshwater as a wash or counter-current liquid. Hence the solubles are, to alarge extent, crowded, so to speak, intothe overow from the firstcentrifugal, the water of which is used primarily, at least, in thesteeps.

In the process disclosedin Fig. 1 of application 674,365, a certainamount df gluten settler water is used in the separating operations forthe reason that there is more of this process water than can beeconomically used for steeping. In Fig. 2 of application 674,365, whichdiscloses the subject matter of the present divisional application,certain arrangements are provided whereby all of the gluten settlerwater goes to the steeps, none being used in the germ, coarse slop or neslop separating operations.

The invention claimed herein is illustrated in the appended drawings inwhich Fig. 1 is a iiow sheet diagram of the process as a whole; and

Fig. 2 is a more detailed diagram of the centrifugal system.

In Fig. 1 the numerals followed by the abbreviation ga1." representthegallons of water present per bushel of corn ground. The indicated waterbalance is of course purely illustrative and subject to variation andmodification. The term "pipe as used herein is intended to include anysuitable conduit, conveyor or other' means for conducting the materialor `liquids from point to point in the system. The term "slop isintended to include the hull fragments, ber and other cellulosicconstituents of the corn. The invention is not confined to anyparticular form of apparatus. The representation of apparatus in thedrawings is wholly diagrammatic. Single units are shown where in actualpractice there will be perhaps quite a large number of units inparallel.

Referring first to Fig. l of the drawings: A designates the steepingsystem which ordinarily consists of a plurality of steep tanks operatedon the counter-current principle; B the mill for breaking up the steepedcorn to free the germs; and C the germ separator. The germs floated oiffrom the liquid in separator C are washed in the germ washing system Dwhich comprises a series of shaking sieves and/or reels. 'I'he rest ofthe grain from the bottom of separator C is screened through coarsesieve E and ne sieve F and the tailings from both sieves are ground inmill G. H represents the coarse slop Wash or separating system,comprising a series of copper covered reels and/or shakers, forseparating starch and gluten from the material ground in the mill G, bywhat may be considered a washing of the slop; J a drain sieve forseparating the fine slop particles from the starch milk flowing from thecoarse slop wash H; and K the fine slop wash, comprising a series ofsilk covered reels and/or shakers for washing the starch and gluten fromthe fine slop removed by drain sieve J. N, O and P are centrifugals. ofwhich there may be any number, for effecting a separation as betweenstarch and gluten. Q is a filter for dewatering and washing the starch.R represents a gluten settler and S a press for pressing out water fromthe gluten removed from the settler R.

In the description of the operation of the process, which follows,reference will be made to the connections between the severalinstrumentalities referred to above.

Operation of procesa-The corn containing 1.3 gallons of water enters thesteeping system A at III and 5.6 gallons of steep water are drawn off atI I and sent to the evaporators (not shown). The steeped corn carrying5.0 gallons of water enters the mill B through pipe I2 and the broken upmaterial passes to the germ separator C through pipeA I3. The germs arefloated oiI from the separator C and pass through pipe Il to the germwash D. The washed germs are discharged from the washing system D at I5with 0.5 gallon of water. Starch milk from the germ system D passesthrough pipe I6 to the separator C to maintain in the separator a properamount of separating fluid of the right density. The rest of the cornpasses from the separator C through pipe I'I to the coarse sieve E, thetailings from which pass through pipe I8 to the mill G while the liquidpasses through pipe I! to the fine sieve F. The liquid from the ne sieveF, consisting of 6.3 gallons of water carrying starch and gluten insuspension, passes into the pipe x, leading to the centrifugal system.'I'he tailings from the fine sieve F pass through `pipe 20 to pipe Iland thence through mill G, 7.2 gallons of water entering the mill withthe corn material. The material fine ground in mill G passes throughpipe 2| to the coarse wash H, from which the coarse slop is dischargedat 22 carrying 0.4 gallon of water. 'I'he liquid from the coarse wash H,15.5 gallons, passes through pipe 23 to the drain sieve J. The liquid(mill starch) from the drain sieve J enters a pipe y, the amount being11.0 gallons. The tailings from the drain sieve J, containing 4.5gallons of water, pass through pipe 2l to the ne wash K from which thefine slop is discharged at 25 containing 0.3 gallon of water. The millstarch from the fine wash K (12.5 gallons) enters the pipe z.

Arranged in pipe y between the drain sieve J and the junction of pipe ywith pipe x, is a concentrator L which may consist .of the settling tankbut is preferably a. filter, the purpose of which is to extract waterfrom the mill starch issuing from the coarse slop system. A certainamount lof mill starch from the fine slop system is also sent to theconcentrator L through pipe 26 which is a branch from pipe z. The amountof mill starch going to the concentrator L is 14.2 gallons, 11.0 gallonsfrom the coarse slop system and 3.2 gallons from the fine slop system.The concentrator L extracts 11.5 gallons of water from the mill starchtreated therein and delivers the concentrated material containing 2.7gallons into pipe y.

The mill starch thus concentrated to a density of about Baum isintroduced into the first centrifugal N through pipe designated my. Theunderflow from centrifugal N, 8.3 gallons, and containing principallystarch, passes through pipe 2l to the second centrifugal O. Theunderflow u through pipe 30.

from centrifugal O passes through pipe 28 to the third centrifugal P,the amount being 8.3

gallons; and the underflow frcmcentrifugal P,

8.3 gallons with a density of about 17 Baum, passes through pipe 29 tothe starch filter Q. Here the starch is first dewatered `and then washedwith 3.1 gallons of fresh water entering The starch is dischargedthrough pipe 3| with 3.1 gallons of water. If desired, the starch may bewashed repeatedly in two or more filters.

12.5 gallons of mill starch light in solubles and containing arelatively small quantity of insolubles, are discharged from the ne slopsystem K through pipe z. 3.2 gallons of this liquid is sent to theconcentrator L, as described, and the remainder, 9.3 gallons, goesthrough pipe z to. the first centrifugal, where it is used 4as a washwater.

Preferably the wash water for the centrifugals O and P is fresh water.By fresh water is intended either tap water or water which containsavery small amount of solids, soluble or insoluble.

In the arrangement shown 6.2 gallons of fresh water are introduced intocentrifugal P through pipe 30a which is a branch of the fresh water line30. The overflow from centrifugal P in pipe 32 divides, 2.8 gallonsbeing returned to the centrifugal P and 6.2 gallons going through pipe33 to the centrifugal O. The overflow from centrifugal O passes intopipe 34, 2.8 gallons going back to the centrifugal O and the restentering pipe 35. Preferably the freshwater introduced into thecentrifugal P enters the `underflow or starch zone of thecentrifugal-machine. Similarly the overflow from centrifugal P tocentrifugal O enters the starch zone of centrifugal O; and the starchliquor from the fine slop system K which is introduced into the firstcentrifugal N, enters the underflow or starch zone of the centrifugal.In Fig. 2 a designates the starch zones of the several centrifugals andb the overflow outlets from the overflow or gluten zones. As a resultthe solubles are concentrated in the overflow from each machine so thatthe underflow, carrying the starch, is relatively free of solubles. Thisconcentration takes place partly through dilution of the material in thestarch zone, but in part through the principle of displacement since theentering starch milk splits off water containing solubles beforemingling with 'wash water in the starch zone. The concentration actuallyobtained in practice cannot in fact be accounted for, mathematically, onthe basis of dilution alone` In the arrangement shown in connection withcentrifugals O and P, the concentration of solubles in the overflow isreduced, due to the recycling of the overflow, in part, through pipes32, 34. The purpose of the recycling is to increase the dilution incentrifugals O and P, in order to repeat the separation as of starchfrom gluten, which is rendered somewhat more difficult because of theuse of a water containing both starch and gluten-the z stream from the-ne slop systemin the iirst centrifuging operait'comes largely from thegerm system, the underfiow from the first centrifugal to the secondcentrifugal will contain such, a small quantity of solubles that it isfeasible to use the circulatory system connected with centrifugals O andP and Ystill reduce' the solubles in the starch going to the starch lterQ suiiiciently so that these solubles can be adequately removed at Q.

The process waters are returned to the process in the following manner:The iiltrates and wash water from starch filter Q, 8.3,gallons, arereturned through pipe 36 to the fine wash. This water will contain aminimum quantity of solubles and hence is used in the last of theseparating operations. 'I'he overflow from the second centrifugal O,(6.2 gallons) which contains the next smallest quantity of solubles, isreturned to the coarse wash H. The waterextracted from the mill starchby the concentrator L, 11.5 gallons, contains a somewhat larger quantityof solubles and 9.0 gallons ofV this water passes through pipe 31 to thegerm wash D, 2.5 gallons going through pipe 38 to the coarse wash H.

The process water which has the highest solubles content, the overflowfrom the first centrifugal N passes through pipe 39 to the settler R,the amount being 10.0 gallons. The gluten from settler R passes throughpipe 40 to press S, from which the gluten is discharged at 4I with 0.-'7gallons of water, the water from the press passing through pipe 42 to apipe 43 which carries the water from the settler R to the steeps A, thetotal amount of steep water being 9.3 gallons.

Because voi' the concentration of part of the mill starch by extractionof water therefrom, the mill starch is centrifuged at such gravity thatthe overflow therefrom will be only 10 gallons, of which 9.3 gallonsgoes to the steeping system. This gives a steep water draw-off of 5.6gallons without sending any of the high solubles water or water whichhas stood in the settlers back to the starch washing separatingoperation; all of this highly infected water being discharged from thesystem through the steeps. The concentration of the mill starch fromabout 5-'l Baum to about 16 Baum has the advantage -of reducing theequipment of centrifugal machines, which are costly and more or lessexpensive to operate and maintain, besides facilitating the separationin each machine as between the starch and gluten, an operation which isquite dililcult with a liquor of low gravity.

Other modifications will occur to those skilled in the art. It is theintention to cover all adaptations of the invention to industries otherthan the starch making industry as well as all changes in the disclosedsystem which are within the scope of the appended claims. However, noclaim is made herein to the process disclosed in Fig. 1 of parentapplication Serial No. 674,365 (Patent #2,100,744) of which the presentapplication is a division.

I claim:

l. The process of manufacturing starch from corn comprising: steepingand comminuting the corn; subjecting the comminuted corn to a series ofseparating operations in water, yielding separate mill starch streamsdieringin their solubles contents; centrifuging the mill starch having ahigh solubles content, after increasing the ratio of insolubles to watertherein, to separate thel and utilizing substantially all of the waterin the overflow from said ccntriiuging operation for stccping corn asthe operations arc continued on fresh material.

2. The process of manufacturing starch from corn comprising steeping andcomminuting the corn; subjecting the comminuted corn to a series ofseparating operations in water, yielding separate mill starch streamsdiffering in their solubles contents; subjecting the mill starch havinga high solubles content to a series of centrifuglng operations in whichthe underflow carryin'g the starch moves in one direction and the washwater overflow, carrying the gluten, in the other direction, afterincreasing the ratio of insolubles to water therein; utilizing millstarch having a lower solubles content as a wash water in saidcentrifuging operations; utilizing the water in the overflow from theflrst of said centrifuging operations for steeping corn as theoperations are continued on fresh material; and utilizing the overflowfrom another of said centrifuging operations in separating operations onthe comminuted corn.

3. Methodof treating bodies of mill starch having different solublescontent to separate gluten and impurities from the starch whichcomprises: increasing the ratio of insolubles to water in the millstarch having the high solubles content; and subjecting this millstarchrto a centrifuging operation in which mill starch having a lowersolubles content is used as a wash water.

4. Method of treating bodies of mill starch having different solublescontent to separate gluten and impurities from the starch whichcomprises: increasing the ratio of insolubles to water in the millstarch having high solubles content; and subjecting the mill starch to acentrifuging operation in which mill starch having a lower solublescontent is used as a wash water and is introduced into the underflowzone of the centrifugal.

5. Method of treating bodies of mill starch having different solublescontent to separate gluten and impurities from the starch whichcomprises: increasing the ratio of insolubles to water in the millstarch having high solubles content by extracting water from mill starchof lower solubles content and mixing the concentrated material with thefirst mentioned mill starch; and subjecting this mixture to acentrifuging operation in which mill starch having a lower solublesconcentration is used as a wash water.

6. Method of treating bodies of mill starch having different solublescontent to separate gluten and impurities from the starch whichcomprises: increasing the ratio of insolubles to water in the millstarch having high solubles content by extracting water from mill starchof lower solubles content and mixing the concentrated material with theflrst mentioned mill starch; and subjecting this mixture to acentrifuging operation in which mill starch having a lower solublesconcentration qis used as a wash water and is introduced into theunderflow zone of the centrifugal machine.

7. Method of treating bodies of mill starch having different solublescontent to separate gluten and imprities from the starch whichcomprises: increasing the ratio of insolubles to water in the millstarch having high solubles content; and subjecting this mill starchto acentrlfuging operation in which mill starch having a lower solublescontent is used as a wash water and subjecting the underflow from thiscentrifuging operation to a ccntrifuging operation in which fresh wateris used as a wash water.

8. Method of treating bodies of mill starch haw ling different solublescontent to separate gluten and impurities from the starch whichcomprises: increasing the ratio of insolubles to water in the millstarch having high solubles content; and subjecting this mill starch toa centriiuging operation in which mill starch having a lower solublescontent is used as a wash water; and subjectirig the underflow from thiscentrifuging Operation to a centrifuging operation in which fresh wateris used as a wash water and in which part of its overflow is returned.

9. Method of treating bodies of mill starch having different solublescontent to separate gluten and impurities from the starch whichcomprises: increasing the ratio of insolubles to water in the millstarch having high solubles content; and subjecting this mill starch toa centrifuging operation in which mill starch having a lower solublescontent is used as a wash water and is introduced into the underflowzone of the centrigufal; and subjecting the underflow from thiscentrifuging operation to a centrifuging operation in which fresh wateris.used as a wash water and is introduced into the underflow zone of thecentrifugal.

lowest solubles content is used as a wash water and is introduced intothe starch zone of the centrifugal. l

11. In the process of manufacturing starch from corn in which the cornafter being steeped and comminuted is subjected to a series ofseparating operations, including a ilne slop separa tion, which yieldsbodies of mill starch having different solubles content, the improvementwhich comprises: increasing the ratio of insolubles to water in thestarch milk having high solubles content; subjecting this mill starch toa centrifuging operation in which the water in the mill starch isdisplaced by the water of mill starch of lower solubles concentrationderived from the flne slop separation which is introduced into thecentrifuging operation as a wash water; subjecting the underflow fromthis ccntrifuging operation to another centrifuging operation; filteringthe starch from the second centrifugm ing operation with fresh water;and using the filtrate from said filtering operation as a wash water insaidflne slop separation.

12. In the process of manufacturing starch from corn in which the cornafter being steeped and comminuted is subjected to a series ofseparating operations, including a fine slop separation, which yieldsbodies of mill starch having different solubles content, the improvementwhich comprises: increasing the ratio of insolubles to water in thestarch milk having high solubles content; subjecting this mill starch toa een trifuging operation in which the water in the mill starch isdisplaced by the water of mill starch of lower solubles concentrationderived from the fine slop separation which is introduced into thecentrifuging operation as a wash water; subjecting the underflow fromthis centrifuging operation to another centrifuging operation. usingfresh water; filtering the starch from the second centrifuging operationwith fresh'water; and using the filtrate from said ltering operation asa wash water in said fine slop separation.

13. In the process of manufacturing starch from corn in which the cornafter being steeped and comminuted is subjected to a series ofseparating operations, including a fine slop separation, which yieldsbodies of mill starch having different solubles content. the improvementwhich comprises: increasing the ratio of insolubles to water in thestarch milk having high solubles content; subjecting this mill starch toa centrifuging operation in which the water in the mill starch isdisplaced by the water of mill starch of lower solubles concentrationderived from the fine slop separation which is introduced into thecentrifuging operation as a wash water; subjecting the underflow fromthis centrifuging operation to another centrifuging operation, usingVfresh water; filtering the starch from the second centrifuging operationwith fresh water; using the filtrate from said filtering operation as awash water in said fine slop separation; and returning part of theoverow from the second centrifuging operation back to such operation.

14. In the process of manufacturing starch from corn in which the cornafter being steeped and comminuted is subjected to germ, coarse slop andfine slop separations, the improvement which comprises: extracting waterfrom the mill starch from the coarse slop separation and adding theconcentrated material to the mill starch from the germ separation;subjecting this mixture to a centrifuging operation ln which the millstarch from the fine slop separation is used as a wash water and isintroduced into the starch zone of the centrifugal; returningsubstantially all of the water in the overflow from this centrifugingoperation to the steeping operation; subjecting the underflow from saidcentrifuging operation to another centrifuging operation in which freshwater is used as a wash water; filtering the starch from the secondcentrifuging operation; and using the ltrate from the filteringoperation as a wash water in the fine slop separation.

15. In the process of manufacturing starch from corn in which the cornafter being steeped and comminuted is subjected to germ, coarse slop andfine slop separations, the improvement which comprises: extracting waterfrom the mill starch from the coarse slop separation and adding theconcentrated material to the mill starch. from the germ separation;subjecting this mixture to a centrifuging operation in which the millstarch from the fine slop separation Ais used as a. wash water and isintroduced into the starch zone of the centrifugal; returningrsubstantially all of the water in the overflow from this centrifugingoperation to the steeping operation; subjecting the underfiow from saidcentrifuging operation to another centrifuging operation in which freshwater is used as a wash water; filtering the starch from the secondcentrifuging operation; using the filtrate from the filtering operationas a wash water in the fine slop separation; using overflow from thesecond centrifuging operation as a wash water for the coarse slopseparation; and using water extracted from the coarse slop mill starchin the germ system.

ALFRED H. KELLING.

